CLASS A FOAM WATER SPRINKLER SYSTEMS

ISSN 1173-5996 CLASS A FOAM WATER SPRINKLER SYSTEMS BY David B Hipkins Supervised by Dr Charley Fleischmann Fire Engineering Research Report 99/9...
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ISSN 1173-5996

CLASS A FOAM WATER SPRINKLER SYSTEMS BY

David B Hipkins

Supervised by

Dr Charley Fleischmann

Fire Engineering Research Report 99/9 March 1999

This report was presented as a project report as part of the M.E. (Fire) degree at the University of Canterbury

School of Engineering University of Canterbury Private Bag 4800 Christchurch, New Zealand Phone 643 364-2250 Fax 643 364-2758

ACKNOWLEDGEMENTS My sincere thanks to my employer, Tyco New Zealand Limited, for having the foresight to invest in the higher education of their employees.

To all my colleagues in the Tyco organisation, world wide, who assisted with professional advice and who rummaged through libraries to source references. A special word of thanks to Joe Behnke and Mitch Hubert (Ansul, Marinette), Jerry Pepi (Grinnell R & D), Ulrich Rieger (Total Walther), and Roger Thomas (TIS, Sydney). To Brenda Hoskins for the professional and cheerful manner in which this report was typed.

A special thank you to William Carey at Underwriters Laboratories, and Dan Madrzykowski at NIST for willingly providing vital information.

To Dr Charles Fleischmann for offering his assistance and guidance to a geographically remote student.

To my wife Joasia, for being understanding and supportive to a man who chained himself to a desk every weekend for a year.

Thank you all.

ii

TABLE OF CONTENTS PAGE Acknowledgments ..............•.•......•......................•..................•.•.•...................................•....... 1 Table of Contents ...•........•.................•.......................•.•......................................................... ii Abstract ••.••.•.••.........•.•......•..........•...•.......•...•.•..........•...•...•..•.•.....•.....•...•................................ v List of Figures and Tables ....•.•......................................•.•...•....•..•.•........•.....................•..•... vi Nomenclature..•...•..•...•......•.•.•••....•.•..•.••.•...•......•...•..••...•...••.........•.....•.•.•...............•....•.•.....•.. x Glossary of Terms and Abbreviations ..........•.......................•.....•..............•.•..••.........•....... xii CHAPTER 1.0 1.1 1.2

Introduction •.••.••..•....•..........................•...•.....•.•......•.•.....•.•...........•..•..........•....... ! Background .......................................................................................................... 1 Aims ofthis Project ............................................................................................. 2

CHAPTER 2.0 2.1 2.2 2.3 2.4 2.5 2.6

Literature Review ............................................................................................... 3 Overview .............................................................................................................. 3 Residential Sprinkler Systems Utilising Class A Foam Solution ........................ 3 Protection of Vertically Racked Plastic Boxes ................................................... .4 Fixed Overhead Compressed Air Foam Systems ................................................ 14 Manual Fire Fighting with Class A Foam ........................................................... 16 Suppression Effectiveness of Class A Foams ..................................................... 22

2.7

Extinguishment ofPlastic Fires with Plain Water and Dilute Solutions of AFFF ........ 27

CHAPTER 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8

Theory .............•...............••........•...•......•.•.......•................................................... 29 Water As An Extinguishing Agent ..................................................................... 29 Sprinkler Droplet Size and Distribution .............................................................. 30 Sprinkler Spray Distribution ............................................................................... 32 Sprinkler System Suppression ............................................................................. 34 Sprinkler Suppression Model .............................................................................. 38 Class A Foam Suppression .................................................................................. 40 Foam Expansion Ratio And Its Effect On Suppression ...................................... 44 Aspirated Foam Stability..................................................................................... 46

CHAPTER 4.0 4.1 4.2

Experimental Apparatus ...........•....•.........•...............................•...................•... 48 Foam Expansion Tests ........................................................................................ 48 Foam Distribution Tests ...................................................................................... 50

iii

TABLE OF CONTENTS CHAPTER 5.0 5.1 5.2

Experimental Procedure ................................................................................... 52 Foam Expansion Tests ........................................................................................ 52 Foam Distribution Tests ...................................................................................... 55

CHAPTER 6.0 6.1 6.2 6.3

Results and Obse(Vations ................................................................................. 56 Foam Expansion Tests ........................................................................................ 56 Foam Distribution Tests ...................................................................................... 58 Discussion ........................................................................................................... 60

CHAPTER 7.0 7.1 7.2 7.3 7.4 7.5

Environmental Considerations ........................................................................ 64 Introduction ........................................................................................................ 64 Toxicity .............................................................................................................. 65 Biodegradability ................................................................................................. 67 Fish Toxicity ...................................................................................................... 68 Conclusion- Environmental Implications ......................................................... 70

CHAPTER 8.0 8.1 8.2 8.3 8.4

System Hardware and Material Compatibility .............................................. 75 Introduction ........................................................................................................ 7 5 Bladder Tank Proportioning ............................................................................... 7 5 Balanced Pump Proportioning ........................................................................... 79 Material Compatibility and Corrosion ............................................................... 81

CHAPTER 9.0 9.1 9.2 9.3 9.4 9.5

Potential Applications ...................................................................................... 86 Introduction ........................................................................................................ 86 Plastic Commodities .......................................................................................... 86 Paper Products and Storage ................................................................................ 88 Limited Water Supply Situations ....................................................................... 89 Warehousing of Stored Rubber Tyres ................................................................ 90

iv

TABLE OF CONTENTS CHAPTER 10.0 10.1 10.2

Recommendations and Conclusions ...........•.......•.•..•...................................... 96 General Conclusions .......................................................................................... 96 Future Research .................................................................................................. 98

REFERENCES .•..............•.•.•.....•............•.....•.•........•...•.•.....•...•...•.......•.•..•......•................... 100 Appendix 1: Physical Properties ........................................................................................... 106 Appendix 2 : Environmental Properties ................................................................................ 109

ABSTRACT Class A foam is often used in the suppression of wildland and structural fires, with manual application methods. This report examines the feasibility of utilising class A foam extinguishing medium in automatic wet pipe sprinkler systems.

Previous researchers report that for certain applications the addition of class A foam solution to a sprinkler system increases suppression effectiveness. Researchers investigating applications with manual fire fighting techniques, using this extinguishing medium, report mixed conclusions.

The integration of class A foam hardware with standard wet pipe sprinkler technology is discussed. Consideration is given to potential corrosion effects and compatibility with sprinkler hardware items. A review of environmental issues revealed that some products are readily biodegradable, while others are not, and that results vary with the test method used.

Tests undertaken to investigate the relationship between the applied sprinkler head pressure and the foam expansion ratio, revealed that only a slight increase in the expansion ratio occurred when the pressure was increased from 50 kPa to 85 kPa. Expansion ratios obtained were similar to those obtained by other researchers using AFFF type foam solution. indicated that the

distribu~ion

Foam-water distribution tests

densities obtained with class A foam sprinkler arrays are within

close proximity to the densities obtained using pure water.

It is suggested that future work in this area should be based around the protection of extreme class

A hazard type fires.

vi

LIST OF FIGURES AND TABLES CHAPTER2 Figure 2.3-1 Figure 2.3-2 Figure 2.3-3 Figure 2.3-4 Figure 2.3-5 Figure 2.3-6 Figure 2.5-1 Figure 2.5-2 Figure 2.6-1

PAGE Polypropylene Plastic Boxes, Rack Stacked ........................................... 5 Test Configuration using an "In Rack" Class A Foam Based Sprinkler System ..................................................................................... 6 Test 3 Fire Development ......................................................................... 9 Fire Damage Associated with Test 1....................................................... 10 Fire Damage_Associated with Test 3 ....................................................... 12 Fire Damage Associated with the Class A Foam Based System .......... ,.......................................................................................... 13 Results of Structural Fire Fighting Room Burn Tests (Time until HRR was 500kW) ................................................................ 20 Results of Structural Fire Fighting Room burn Tests (Quantity until HRR was 500kW) ........................................................... 21 Schematic of the Nozzle Arrangement for the Crib Fire Tests ............... 25

CHAPTER3 Figure 3.3-1 Figure 3.3-2 Figures 3.3-3a,b,c Figure 3.3-4 Figure 3.5-1 Figure 3.6-1 Figure 3.6-2 Figure 3.7-1 Figure 3.7-2

Typical Spray Pattern for a Standard Spray Type Sprinkler ................... 32 Variation in Mass Flux Density as a Function of Radial Distance ................................................................................................... 3 3 Effect of Discharge Pressure on Floor Level Spray Patterns .................. 34 Flow Contours for a Standard Pendant Spray Sprinkler ......................... 35 610mm Wood Crib Heat Release Rates at Varying Densities ............... .40 Surface Tension Valves for Water and Class A Foam Solution ............ .41 Surface Contact Angle ............................................................................. 42 Aspirated Foam Formation for a Foam Water Sprinkler ........................ 44 Mesh type Diffuser Aspirating Head ...................................................... .45

CHAPTER4 Figure 4.1-1 Figure 4.1-2 Figure 4.2-1

Schematic Representation of the Test Configuration .............................. 48 Foam Slider Collector Board ................................................................... 50 Foam Distribution Test Array ................................................................. 51

CHAPTERS Figure 5.1-la,b

Position ofFoam Slider Board ................................................................ 54

vii

LIST OF FIGURES AND TABLES CHAPTER6 Figure 6.1-1 Figure 6.1-2 Figure 6.2-1 Figure 6.2-2 Figure 6.3-1 Figure 6.3-2

PAGE Expansion Ratio as a Function of Pressure ............................................. 57 Foam Expansion Tests .................... ,....................................................... 58 Foam Distribution Test Number 1 .......................................................... 59 Foam Distribution Test Number 2 .......................................................... 60 Density Variation for Tests 1 and 2 ......................................................... 62 Density_Variation for Tests Conducted by Factory Mutual with Plan Water ....................................................................................... 63

CHAPTERS ·.Figure 8.2-1 Figure 8.3-1

Typical Schematic of Hardware Arrangement for Class A Sprinkler System, utilising a Bladder Tank ............................................ 78 Typical Schematic for Balanced Proportioning with a Pumped Concentrate Supply and In Line Pressure Proportioner ............................................................................................. 79

CHAPTER9 Figure 9.5-1 Figure 9.5-2 Figure 9.5-3

Tyre Storage Test Configuration- FMRC Test 1 ................................................................. 92 Tyre Storage Test Configuration- FMRC Test 2 ................................................................. 92 TyrC? Storage Test Configuration- FMRC Test 3 ................................................................. 93'

viii

LIST OF FIGURES AND TABLES CHAPTER2 Table 2.3-1 Table 2.3-2 Table 2.4-1 Table 2.5-1 Table 2.5-2 Table 2.6-1 Table 2.7-1

PAGE Results of Full Scale Fire Tests with Racked Plastic Boxes ....................................................................................................... 8 Results of Full Scale Fire Tests with Racked Plastic Boxes and Class A Foam ................................................................................... 11 Summary of Kim and Dlugogorski's Class A Confined Fire Tests .... "" ......................................................................................... 15 Results of "Salem Tests" ......................................................................... 17 University of Wuppertals Room Fire Test Results ................................. 18 Size Distribution of Smoke from Fire Suppressant Foam Agents Extinguishment ........................................................................... 24 Extinction Time for Common Plastics with Plan Water and 0.2% AFFF Solution ......................................................................... 27

CHAPTER3 Table 3.2-1 Table 3.7-1

Estimated and Measured Valves of Mean Sprinkler Droplet Size ............................................................................................. 31 Foam Expansion Ratios for Various Discharge Hardware Devices .................................................................................................... 46

CHAPTER4 Table 4.1-1

Summary_ of Equipment used in Foam Expansion Experiments ............................................................................................. 49

CHAPTER6 Table 6.1-1 Table 6.1-2 Table 6.2-1 Table 6.2-2

Results ofF oam Expansion Tests ........................................................... 56 Results of 25% Drain Tests ..................................................................... 57 Foam Distribution Test Number 1 Results .............................................. 58 Foam Distribution Test Number 2 Results .............................................. 59

CHAPTER 7 Table 7.5-1 Table 7.5-2

Table 7.5-3

Estimates of the Quantity of Class A Foam Discharged from a Sprinkler System, based in 8 Heads Operating .................................... 71 Estimates of the Quantity of Class A Foam Discharged from a Sprinkler System based on Typical Sprinkler System Design Parameters ............................................................................................... 72 Toxicity Characteristics of Fire Ground Run-OffWater and Class A Foam Solution .......................................................... ,~-" .............. 73

ix

LIST OF FIGURES AND TABLES CHAPTERS Table 8.4-1 Table 8.4-2 Table 8.4-3 Table 8.4-4

PAGE Uniform Corrosion Rates for Steel and Brass with Fresh Concentrate .................................................................................... 82 Uniform Corrosion Rates for Steel and Brass with 1% Foam Solution ................................................................................... 83 Typical Materials Exposed to Foam Concentrate in Class A Foam System ............................................................................. 84 Typical Materials Exposed to Foam Solution in a Class A.Foam Sprinkler System.............................................................. 85

CHAPTER9 Table 9.5-1 Table 9.5-2

Draft Results of the Class A Type Foam Products Tested on Stacked Tyres .......................................................................... 94 NIST Stacked Tyre Fire Test Results - Summary ................................... 95

X

NOMENCLATURE A

=area m 2

C

=imperical constant (approximately 3.21)

C,R0 ,R 1 = Rosin-Rammler coefficients d

=

droplet diameter

D

=

sprinkler orifice diameter (mm)

D

=

Sprinkler orifice diameter (mm)

d111

=

mean droplet diameter (mm)

dm

=

volume mean droplet diameter

E

=

f(d)

=

expansion ratio dropletsize distribution function

F(r,t) = bubble size distribution function He

=

crib height (mm) proportionality constant (inclusive of ll P)

K m

=meters

P

= orifice pressure (kglm.sec. 2)

P

=pressure kPa

ll P =pressure difference

Q =flow rate (m 3/sec) Q

=flow rate !!min)

Q (tacJ

=

Q (t-tacJ

r

=

re rs

= =

=

heat release rate at the time ofsprinkler activation (tacJ; Kw post sprinkler activation heat release rate of the fire, kW

bubble radius large bubble radius small bubble radius

xi

NOMENCLATURE

U= Water velocity through the sprinkler orifice (mlsec) Vfs =volume offoam solution Va

volume of air

=

w"

=

spray density (llminlm 2)

We= Weber number

y

=

pw

surface tension =

water density (1 000kg/m3)

75%0li' .. . MINiMVM YES YES YES YES YES YES YES YES YES YES YES YES YES YES YES YES

..

-

59

Table 6.2-2: Foam Distribution Test Number 2. TRAY NO.

TRAY MASS (Kb)

1 2 3 4 5 6 7 8 9

10 11 12 13 14 15 16 TOTAL AVERAGE MINIMUM SPECIFIED 75%MINIMUM

3.210 3.210 3.230 3.215 3.215 3.215 3.220 3.220 3.210 3.220 3.220'· 3.210 3.225 3.225 3.220 3.210

GROSS MASS (Kg) 7.83 9.41 9.55 7.365 8.75 10.145 10.52 8.37 9.005 11.905 15.645 13.485 8.51 11.375 17.59 16.32

NETT MASS (Kg)

DENSITY L/inin!M2

>75% OF MINIMUM

4.620 6.200 6.320 4.150 5.535 6.930 7.300 5.150 5.795 8.685 12.425 10.275 5.285 8.150 14.370 13.110 124.300

4.89 6.57 6.69 4.40 5.86 7.34 7.73 5.45 6.14 9.20 13.16 10.88 5.60 8.63 15.22 13.88 131.65 8.228 6.112 4.584

YES YES YES NO YES YES YES YES YES YES YES YES YES YES YES YES

Figure 6.2-1: Foam Distribution Test Number 1.

60

Figure 6.2-2: Foam Distribution Test Number 2.

6.3 •

Discussion Foam Expansion Tests

Figure 6.1-1 indicates that there is an increase in the foam expansion ratio when the applied pressure is increased from 50kPa to 85kPa. Beyond this pressure, higher expansion ratios were not obtained with further pressure increases.

The results of any previous experimental work relating to foam expansion, with class A foam and standard sprinklers, could not be found. Tests undertaken by Factory Mutual Research Corporation with 3% AFFF foam solution and standard sprinklers resulted in expansion ratios in the range of2.2-2.3. 40 These tests were conducted at a pressure of97kPa and an elevation of 18.3m. These results are very similar to the tests undertaken in this research at a similar pressure, (ie., tests 1 and 2 gave expansion ratios of2.12 and 2.28 at a pressure of 85kPa).

There is a significant difference between the elevation level of the sprinkler heads in the Factory Mutual tests 40 (ie., 18.3m elevation), compared to the class A foam tests conducted in this project (ie., 2.7m elevation). The effect of elevation on expansion ratio could not be examined in the test series due to physical limitations of the building in which the tests were conducted.

61

It was anticipated that further slight increases in the expansion ratio would have occurred as the

pressure was increased beyond 85k:Pa. The limitation associated with the pump as detailed earlier may have had an affect on the results of the tests. In tests 1-4 the pump had the capacity to flow all four heads at the required pressure. In the case where only two or one head was operated the overall density associated with the discharge array would have been lower. In this situation the time required to fill the foam collector with foam would have ·been longer. With such a relatively low expansion foam, this additional time required to fill the foam collector would have given the existing foam more time to drain. Such an effect would have an impact on the 25% drain times and the expansion ratio results.



25% Drain Times

In all of the tests the expanded foam exhibited fast drain times. Tests undertaken with the foam collector apparatus and pure water showed that 25% of the collector capacity could be drained in 15 seconds. Similar times were obtained for most of the foam tests conducted, hence the drain times can be categorised as being "instantaneous".

Tests undertaken by Factory Mutual Research Corporation with 3% AFFF and standard sprinklers obtained 25% drain times between 0.5-1.3 minutes (30-78 seconds).40



Distribution Tests

Tests 1 and 2 achieved average densities of 8.3 l/min/m2 and 8.21/min/m2 • These valves are in excess of the minimum average valve stipulated by UL Standard 199 (ie., 6.1 l/minlm2). Tests conducted by Factory Mutual Research Corporation, with the same heads at the same flow rate with pure water, gave average density figures of 10.6 l/min/m2, 11.81 l/min/m2, 8.9 l/minlm2 and 8.6 l/min/m2 for four repetitive tests that were undertaken. 45

62

UL Standard 199 also stipulates that all of the pans must achieve a minimum density of 75% of the required average valves. 32 This requirement equates to a density of 4.58 l/min/m2 being obtained in all collection pans. In test number 1 this minimum valve was achieved in all trays. In test number 2 all but one of the trays (tray number 4) achieved this requirement. The density obtained in tray number 4 was slightly under the minimum valve (ie., 4.4 l/min/m2).

The results show that there was considerable variation between the densities achieved in identical tray numbers for the two tests. Figure 6.3-1 shows this variation graphically. No logical explanation could be found for this variation. Tests conducted by Factory Mutual with pure water produced results with similar valves when repeated. 45 These results are shown in figure 6.3-2.

Figure 6.3-1: Density Variation for Tests 1 and 2.

DENSITY VARIATION FOR TEST 1& 2

N

-

16.00 14.00

::2: 12.00

z

lEJ TEST 1 DENSITY Llmin/M2 • TEST 2 DENSITY Llmin/M2

::2: 10.00

-~ ::J

en z

w 0

8.00 6.00 4.00 2.00 0.00 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 TRAY NO

63

Figure 6.3-2: Density Variation for Tests Conducted by Factory Mutual with Plain Water. 45

DENSITY VARIATION FOR TESTS CONDUCTED BY FMRC WITH PLAIN WATER

-

25.00

N

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